1. Field of the Invention
The present invention relates to a method for driving a liquid crystal display monitor and a related driving device, and more particularly, to a driving method and related driving device initiating a charge sharing function for decreasing power consumption when the liquid crystal display monitor is driven by a column inversion procedure.
2. Description of the Prior Art
The advantages of a liquid crystal display (LCD) include lighter weight, less electrical consumption, and less radiation contamination. Thus, LCD monitors have been widely applied to various portable information products, such as notebooks, mobile phones, PDAs, etc. In an LCD monitor, incident light produces different polarization or refraction effects when the alignment of liquid crystal molecules is altered. The transmission of the incident light is affected by the liquid crystal molecules, and thus magnitude of the light emitting out of the liquid crystal molecules varies. The LCD monitor utilizes the characteristics of the liquid crystal molecules to control the corresponding light transmittance and produces gorgeous images according to different magnitudes of red, blue, and green light.
Please refer to FIG. 1, which is a schematic diagram of an LCD monitor 10 according to the prior art. The LCD monitor 10 includes a display panel 100, a timing controller 102, a source driver 104, and a gate driver 106. The display panel 100 is constructed by two parallel substrates, and the liquid crystal molecules are filled up between these two substrates. One of the substrates includes a plurality of data lines D1˜Dm and a plurality of gate lines G1˜Gn that are perpendicular to the data lines D1˜Dm. The display panel 100 has thin film transistors (TFT) 114 installed in each intersection of the data lines D1˜Dm and gate lines G1˜Gn. In other words, the TFTs 114 are arranged in a matrix format on the display panel 100. The data lines D1˜Dm correspond to columns of the LCD monitor 10, the gate lines G1˜Gn correspond to rows of the LCD monitor 10, and each of the TFTs 114 corresponds to pixels P11˜Pmn. In addition, the two substrates of the display panel 100 filled up with liquid crystal molecules can be considered as an equivalent capacitor 116.
The operation of the prior art LCD monitor 10 is described as follows. The timing controller 102 generates corresponding control signals and clock signals according to image data desired to be displayed on the display panel 100. According to the signals received from the timing controller 102, the source driver 104 and the gate driver 106 then respectively generate driving signals and gate signals to corresponding data lines and gate lines, for turning on the TFTs 114 and keeping a voltage difference of the equivalent capacitors 116, to change the alignment of liquid crystal molecules and light transmittance, so that the image data can be displayed in the display panel 100. For example, the gate driver 106 outputs a pulse to the gate lines G1˜Gn for turning on the TFTs 114. Therefore, the driving signals generated by the source driver 104 can be inputted to the equivalent capacitor 116 through the data lines D1˜Dm and the TFTs 114, and then the voltage difference kept by the equivalent capacitor 116 can adjust a corresponding gray level of the related pixel. In addition, a magnitude of each of the driving signals inputted to the data lines D1˜Dm corresponds to different gray levels.
If the LCD monitor 10 continuously uses a positive voltage to drive the liquid crystal molecules, the liquid crystal molecules will not quickly change a corresponding alignment according to the applied voltages as before. Thus, the incident light will not produce accurate polarization or refraction, and the quality of images displayed on the LCD monitor 10 deteriorates. Similarly, if the LCD monitor 10 continuously uses a negative voltage to drive the liquid crystal molecules, the liquid crystal molecules will not quickly change a corresponding alignment according to the applied voltages as before. Thus, the incident light will not produce accurate polarization or refraction, and the quality of images displayed on the LCD monitor 10 deteriorates. In order to prevent the liquid crystal molecules from being polarized, the LCD monitor 10 must alternately use positive and the negative voltages to drive the liquid crystal molecules.
Please refer to FIG. 2 and FIG. 3, which are schematic diagrams of a column inversion procedure according to the prior art. Blocks 20 and 30 show polarities of pixels in the same part of two successive image frames. Comparing the blocks 20 and 30, when the display panel 100 is driven by the column inversion procedure, polarities of pixels in a column are uniform and change to opposite polarities as a frame changes. Note that polarities of pixels in different columns are opposite. Since polarities of pixels in a same column are uniform, the display panel 100 driven by the column inversion procedure has the advantages of low power consumption. However, the display panel 100 driven by the column inversion procedure still has the shortcomings of high power consumption in certain frames, which causes a heat problem in the display panel 100 of the LCD monitor 10.
Please refer to FIG. 4, which is a schematic diagram of driving voltage signals of the data lines D1˜Dm outputted by the source driver 104 in the same frame during the column inversion procedure. In FIG. 4, the transverse axle represents time, the vertical axle represents voltage level, Vs indicates a maximum driving voltage, and the data lines D1˜Dm are divided into positive odd data lines (D1, D3, . . . , and Dm-1) and negative even data lines (D2, D4, . . . , and Dm). The maximum and minimum voltage of the negative data lines (D2, D4, . . . , and Dm) are Vs/2 and 0 respectively, and the maximum and minimum voltage of the positive data lines (D1, D3, . . . , and Dm-1) are Vs and Vs/2 respectively. As can be seen, the source driver 104 provides Vs/2 for the negative data lines (D2, D4, . . . , and Dm) to receive the maximum and minimum voltage in the same polarity when the display panel 100 performs the column inversion procedure. Similarly, the source driver 104 provides Vs/2 for the positive data lines (D1, D3, . . . , and Dm-1) to receive the maximum and minimum voltage in the same polarity. Therefore, the data lines of the same polarity can have a voltage change of Vs/2. Meanwhile, the LCD monitor 10 has the largest loading since the source driver 104 consumes the largest power at this point of time, which causes a heat and power consumption problem in the source driver 104.